This invention relates to the treatment of body lumens and, more particularly, to the endovascular placement of a prosthetic graft within vasculature for the purpose of repairing the same.
It is well established that various fluid conducting body or corporeal lumens, such as veins and arteries, may deteriorate or suffer trauma so that repair is necessary. For example, various types of aneurysms or other deteriorative diseases may effect the ability of the lumen to conduct fluids and, in turn, may be life threatening. In some cases, the damage to the lumen is repairable only with the use of prostheses such as an artificial vessel or graft.
For repair of vital lumens such as the aorta, surgical repair is significantly life threatening or subject to significant morbidity. Surgical techniques known in the art involve major surgery in which a graft resembling the natural vessel is spliced into the diseased or obstructed section of the natural vessel. Known procedures include surgically removing the damaged or diseased portion of the vessel and inserting an artificial or donor graft portion inserted and stitched to the ends of the vessel which were created by the removal of the diseased portion. More recently, devices have been developed for treating diseased vasculature through intraluminal repair. Rather than removing the diseased portion of the vasculature, the art has taught bypassing the diseased portion with a graft and implanting the graft within the vasculature.
It has been found that many abdominal aortic aneurysms extend to the aortic bifurcation. Accordingly, a majority of cases of endovascular aneurysm repair employ a graft having a bifurcated shape with a trunk portion and two limbs, each limb extending into separate branches of vasculature.
Placement of a bifurcated endovascular aortic graft within vasculature is rendered difficult by the diverse variation and anatomical morphology present in different patients. In order to implant a correctly sized graft, one must consider the neck diameter, neck length, limb diameters and limb lengths of the target vasculature. For example, the left iliac diameter and length may differ substantially from the right iliac diameter and length in the same patient and the same must be considered in sizing a graft. The calculated permutations of neck and limb dimensions require to adequately treat all patients has been estimated to number approximately thirteen thousand. It is not practical, however, to manufacture and store multiple numbers of all thirteen thousand sizes of bifurcated aortic grafts, due to cost and storage considerations.
Determination of true aortic sizes is most accurately performed through an aortogram, with delineation of aortoiliac anatomy via fluoroscopic imaging of injected contrast dye. This generally occurs before or at the time of endovascular graft placement. Staging an aortogram prior to the graft placement procedure may allow a custom sized graft to be manufactured. For example, a patient may be brought in for an aortogram a significant time (e.g., one month) prior to a scheduled elective endovascular graft procedure for definitive aortoiliac sizing. A specially sized graft may be manufactured and inserted into a jacketed catheter delivery system for subsequent use.
The difficulty with this approach is twofold. First, the patient must be brought into the hospital for an additional catheter procedure, adding inconvenience and expense to the treatment regime. Second, the sizing procedure results in a delay in the treatment of the patient.
Accordingly, there exists a need for a graft that can be customized on site at the time of an implant procedure. The present invention addresses this and other needs.
Briefly and in general terms, the present invention is embodied in an adjustable customized endovascular graft. The graft of the present invention is adjustable lengthwise or longitudinally and widthwise or laterally to affect a change in diameter to provide a structure configured to adapt to irregularities in anatomy.
In one aspect of the invention, the graft is an oversized tube, tapered, unibody bifurcated, modular bifurcated, or modular tapered graft. The graft is configured with at least one or a plurality of releasable pleats along the graft body or a portion thereof. The pleats are strategically placed during manufacture to facilitate the modification of the diameter and length of various portions of the graft.
In a preferred embodiment, an outside surface of the graft of the present invention is configured with pleats across the graft. Further, the pleats are configured such that pockets formed thereby are directed away from the path of flow of blood through the interior of the graft. In this way, the graft is provided with a relatively smooth interior profile for optimal flow characteristics.
Construction of the pleats may be achieved by various methods. It is contemplated that the pleats may be formed by sewing a looped stitch in the graft wall that unravels when a free end of the stitch is pulled. A running stitch can also be used particularly in the transverse pleats that are short in length. Conventional suture material may be used for this purpose. Such stitching is employed to maintain pleated sizes and shapes when the graft is filled with pressurized blood.
A catheter embodying a jacket for receiving the adjustable graft of the present invention is contemplated to be employed for delivering the graft within vasculature. In a preferred embodiment, the jacket is configured with a plurality of holes which provide access to the pre-placed stitches forming the pleats in the adjustable graft. The tail of the suture forming the respective pleats extends through such a hole, with the suture knot residing inside the jacket. When one desires to release a given pleat, tension is applied to the corresponding suture tail to pull the knot out of the hole in the jacket and allow the pleat forming stitch to be cut and pulled out of the graft. Alternatively, a crosspiece of metal or plastic may be provided exterior each of the access holes wherethrough a portion of a stitch forming a pleat is routed and placed into engagement with the crosspiece. Each access hole is contemplated to be separately identified to thereby provide a reference respecting the location and purpose of a particular pleat. Releasing the crosspiece and pulling the suture yields desired graft dimensions.
In an alternative embodiment, the adjustable graft may include flared ends. When so configured, the adjustable graft can accommodate a greater range of diameters found in vasculature.
Other features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.